Supreme Court Justice Stephen Breyer did not address the biggest question facing the nation's high court—the battle for late Justice Antonin Scalia's seat—at Columbia on Thursday.

Instead, Breyer stuck to a familiar script on the importance of using international law to inform U.S. cases, in conversation with University President Lee Bollinger and SIPA Dean Merit Janow at the School of International Affairs' annual Silver Lecture at Casa Italiana. The subject, which had been a point of frequent debate between Breyer and Scalia, was the focus of Breyer's September 2015 book, “The Court and the World: American Law and New Global Realities.”

“The best way to protect American values is to know what's going on outside our shores,” Breyer said, telling the audience of Columbia Law students and professors that it was increasingly important to consider international law.

To illustrate his point, Breyer went through the history of the Supreme Court's rulings about presidential power in wartime, restating remarks he had given in the press tour for his book last fall.

He zeroed in especially on 1944's Korematsu v. United States, in which the court upheld President Franklin D. Roosevelt's use of internment camps during World War II. Breyer frequently discusses his dismay with the Korematsu decision, even evoking the controversial case while sidestepping a question last December about presidential hopeful Donald Trump's Muslim ban.

“I think we can't go back to Korematsu. That, in my opinion, would be simply terrible,” he said. “The least we can do is find out more than we know about security problems, and look and see what other countries do. Maybe we'll learn something—we're not the only ones in the world facing these kinds of threats, nor are we the only ones who have traditions of civil liberties and democracy.”

Columbia Law School Dean Gillian Lester asked Breyer whether it would be going too far to cite a foreign case in a U.S. Supreme Court decision.

“I can refer to what I want. That's not a problem,” Breyer said. “If it's relevant, fine. Use it.”

He argued that the next generation of lawyers will be responsible for shaping the uncoded system of international law known as comity, which has changed during his tenure on the court.

He cited the Supreme Court's decision in Morrison v. National Australia Bank, a 2010 case in which the court struck down a Securities and Exchange Commission rule that said U.S. securities law could be applied to cases outside U.S. borders.

“We had briefs from all over the world ... that said, Stay out of it,'” Breyer recalled. “Comity now is not simply, Stay out of it, it's theirs.' It's how you interpret an American statute given what other people are doing, so you can harmonize and further the similar advance of similar areas of law in many different countries.”

Breyer sided with the majority to uphold Bollinger's affirmative action policy at the University of Michigan in Grutter v. Bollinger in 2003.

“I'd like to thank you for inviting me to Columbia. In preparation, about three or four weeks ago, I went to see Hamilton,'” Breyer said. “You know, he went to Columbia. Though there wasn't a law school at that time—think of what he could have done with his mind.”